For fixed-wing aircraft, flight guidance and navigation displays with a tunnel-like display of a planned flight path in space, so-called tunnel-in-the-sky displays, are known. However, even for fixed-wing aircraft, flight guidance and navigation systems comprising tunnel-in-the-sky displays have not yet been approved for instrument flight.
Due to their tunnel-like display of the planned flight path, the known flight guidance and navigation displays, hereinafter also referred to as three-dimensional flight guidance and navigation displays, provide information on lateral (heading) and vertical (flight altitude) guidance that comprises intuitive visualisation for the pilot. The known three-dimensional flight guidance and navigation displays are associated with a disadvantage in that they do not furnish any information about longitudinal flight guidance and navigation (flight speed/position-time). There is a further disadvantage in that the known three-dimensional flight guidance and navigation displays were essentially developed for fixed-wing aircraft, and do thus not take into account the aerophysical characteristics of a helicopter.